Unreal and Unity are both very, very good engines. Now that the barrier to entry is so low for both of them, which engine to use is fairly subjective.
I'd suggest selecting a simple gameplay mechanic from your game, then try and implement it each engine. It may take you a bit more time but you'll get a feel for each engine's workflow, and be in a much better position to choose. Time well spent
For a person with some coding experience at least, this is the approach to take.